Data storage in the computer industry is accomplished in a number of ways. For example, data may be stored on tape, compact disk, "floppy" or "hard" disk, and the like. Oftentimes, data storage media which is transferrable from one location to another is housed within a parallelepiped-shaped cartridge. However, it is to be understood that the term "cartridge" as used herein includes other types of storage media and should not be construed to limit the present invention to be utilized only with data cartridges.
Data storage systems are used to store data storage media devices such as data cartridges at known locations and to retrieve desired cartridges so that data may be written to or read from the cartridges. Such data storage and handling systems are often referred to as "juke box" data storage systems, particularly if they can accommodate a large number of individual data cartridges.
A data storage handling system may include a cartridge engaging assembly or "picker" which is adapted to retrieve a data cartridge and transfer the cartridge from one location to another, such as from a cartridge storage array to a read/write drive. The drive may then be used to read data from or write data to the cartridge. Once the read/write operation is complete, the cartridge engaging assembly may withdraw the data cartridge from the drive and return it to the appropriate location within the cartridge storage array. Cartridge engaging assemblies are described in U.S. Pat. No. 5,010,536 for CARTRIDGE HANDLING SYSTEM, U.S. Pat. No. 6,160,786 for CARTRIDGE ENGAGING ASSEMBLY WITH RACK DRIVE THUMB ACTUATOR SYSTEM and U.S. Pat. No. 6,157,513 for IMPROVED THUMB REFERENCING AND DRIVE SYSTEM, which are each hereby specifically incorporated for all that is contained therein.
There are some cartridge engaging assemblies which can access only a single plane of cartridge locations. Such a cartridge engaging assembly may be connected to a drive assembly which translates the assembly in a linear direction along a row of cartridge locations. There are also several different types of cartridge engaging assemblies which are capable of accessing more than one plane of cartridge locations.
For example, a "pass-through" cartridge engaging assembly is capable of gripping cartridges which are aligned opposite one another along two parallel planes. Typically, friction belts or rollers are used to grip and translate the cartridges within the cartridge engaging assembly. The two-plane access results in a more dense product architecture. However, there are a number of problems associated with "pass-through" cartridge engaging assemblies. The design of the assembly necessarily becomes significantly more complex and is subject to greater unreliability due to this complexity. The number of components in such an assembly is typically more than twice the number of components in a single-plane cartridge engaging assembly. Furthermore, friction gripping of the cartridges relies on developing a consistently high enough normal force and fiction coefficient in order to extract, translate, and insert media from and into storage locations and read/write drives. In addition, since "pass-through" cartridge engaging assemblies are not adapted to rotate the cartridges, cartridges will be facing front-forward in one plane and front-rearward in the other plane. Thus, cartridge storage locations must either be adapted to accept cartridges in both orientations (front-rearward and front-forward), or two different types of cartridge storage locations must be included in a system with a pass-through cartridge engaging assembly. Furthermore, in systems in which the cartridges are scanned by some type of tracking device such as a bar code reader, the system must be provided with two tracking devices (one facing each plane of cartridges), and cartridges must have bar code labels on both the front and the back thereof. Alternately, a tracking device may be located within the cartridge engaging assembly, whereby a cartridge with a bar code label on only one side thereof (usually the front) must be loaded into the cartridge engaging assembly in order to read the label. This results in a significant time delay in all but the smallest of systems. A tracking system for a cartridge engaging assembly is shown and described in U.S. patent application Ser. No. 09/292,781, now abandoned, for LOW POWER ILLUMINATOR, which is hereby specifically incorporated for all that is contained therein.
Another type of cartridge engaging assembly which is adapted to access more than one plane of cartridge locations is shown and described in U.S. Pat. No. 6,025,972 entitled MULTI-PLANE TRANSLATING CARTRIDGE HANDLING ASSEMBLY, which is hereby specifically incorporated for all that is contained therein. This assembly is provided with a track which is located along two or three planes of cartridge locations. The assembly includes a pinion gear which engages the track and allows the assembly to be translated along the multi-plane track. A disadvantage of this assembly is that, in order to access two cartridge locations located opposite one another in parallel planes, the assembly must be translated half-way around the track. It would be much more advantageous to provide a cartridge engaging assembly which is able to simply rotate to access an opposing cartridge location.
Thus, a need exists for a cartridge engaging assembly which is adapted to rotate in order to access cartridge locations in more than one plane. Such a system should be simply constructed, with a minimal number of components.